Specific aims of the Measurement and Study Coordination Core (Core B) involve facilitating comparative and replicable research based on coordinated or pooled-data analysis of longitudinal studies of aging. The focus is on developing tools and documentation to support the identification of relevant studies for answering particular questions and to enable rigorous cross-study comparison and data harmonization activities. A purpose-built website enabling organization and aggregation of study and measurement related information will be created (SA1, infrastructure/tools) by the International Harmonization Platform (IHP) team, adapting as necessary the methods, web-based tools and software developed by this group of experts. The website will include and provide access to an extensive searchable cross-study catalogue (SA2, content) for organizing and comparing information about the variables collected by each study, and a contextual database (SA3, content) that will include historical country (or in limited cases region) level information that can be used in addressing cross-national heterogeneity in parallel and pooled analyses. The contextual database will initially be focused on major health and mortality characteristics, average physical height, and standard educational attainment over the range of birth cohorts represented in the lALSA and HALCyon networks. The website will also include a framework to assist in management of all steps of the data harmonization process (SA4, harmonization activities). The website developed by this core will provide a central communication portal for investigators involved in the proposed analyses of affiliated datasets and will include tracking of permissions for data usage from collaborating studies, project management, and a record of published and in progress manuscripts (managed by Core A). RELEVANCE (See instructions): This Core represents the central resources and activities related to creating an international harmonization platform for longitudinal studies of aging. It will provide key support to the subprojects that make up this program project and will furnish essential resources to all researchers eingaged in collaborative interdisciplinary research using data collected in major longitudinal studies on aging.